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Evidence That a Miniature CuI Metalloprotein Undergoes Collisional Electron Transfer in the Inverted Marcus Region


  • This work was partially supported by NSF grant no. CHE-0455441 (M.Y.O.), ACS-PRF grant no. 34901-AC (M.Y.O.), and AHA grant no. 0455900T (B.R.G.). A.K.P. is an NSF-GK-12 fellow (NSF-DGE-02-31875). We thank Prof. M. A. J. Rodgers for helpful discussions and Prof. F. Castellano for use of the laser facilities.


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It takes two to transfer: A synthetic CuI metalloprotein undergoes bimolecular photoinduced electron transfer in the inverted Marcus regime. The buried CuI4S4(N/O)4 cofactor (purple) has a high reorganization energy and experiences weak electronic coupling to electron acceptors (Q) in the bulk solvent. This lowers kET below the diffusion limit and allows observation of inverted Marcus behavior.